feat: 盈亏比与亏损额度展示，市价FAK报单，修复止盈止损保存失败

Co-authored-by: Cursor <cursoragent@cursor.com>

vnpy_bridge.py

@@ -825,10 +825,11 @@ class CtpBridge:
             raise ValueError(f"未知开平: {offset}")
 
         use_market = (order_type or "limit").lower() == "market"
-        ot = OrderType.LIMIT
         if use_market:
+            ot = OrderType.FAK
             price = self._aggressive_limit_price(ths_code, sym, ex_name, d, tick, price)
         else:
+            ot = OrderType.LIMIT
             price = round_to_tick(float(price), tick)
         if price <= 0:
             raise ValueError("委托价格无效，请检查行情或手动填写价格")
@@ -929,7 +930,8 @@ def ctp_get_account(mode: str) -> dict[str, Any]:
 
 def ctp_list_positions(mode: str, *, refresh_if_empty: bool = True) -> list[dict[str, Any]]:
     b = get_bridge()
-    b.ensure_connected(mode)
+    if b.connected_mode != mode or not b.ping():
+        return []
     return b.list_positions(refresh_if_empty=refresh_if_empty)